BARS apparatus

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Schematic of a BARS system.
Two BARS devices, one open for loading or unloading and the other closed.

BARS (or "split sphere") is a high-pressure high-temperature apparatus usually used for growing or processing minerals, especially diamond. The name is a transliteration of a Russian abbreviation БАРС = Беспрессовая Аппаратура высокого давления "Разрезная Сфера" (press-free high-pressure setup "split sphere"). Typical pressures and temperatures achievable with BARS are 10 GPa and 2500°C.[1]

The BARS technology was invented around 1989–1991 by the scientists from the Institute of Geology and Geophysics of the Siberian branch of the Academy of Sciences of the USSR.[1] In the center of the device, there is a ceramic cylindrical reaction cell of about 2 cm3 in size. The cell is placed into a cubic-shaped pressure-transmitting material, which is pressed by elements made from cemented carbide (VK10 hard alloy).[2] The outer octahedral cavity is pressed by 8 steel sectors. After mounting, the whole assembly is locked in a disc-type barrel with a diameter ~1 meter. The barrel is filled with oil, which pressurizes upon heating; the oil pressure is transferred to the central cell. The central cell is heated up by a coaxial graphite heater. Temperature is measured with a thermocouple.

The growth rate for 5 carats (1.0 g) type Ib (yellow, nitrogen-rich) crystals using Fe–Ni catalyst reaches as high as ~20 mg/h towards the end of 100 h growth cycle, i.e. crystals of 5 carats (1.0 g) to 6 carats (1.2 g) can be grown in less than 100 h.[3]

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  1. ^ a b N. Pal'yanov; et al. (2002). "Fluid-bearing alkaline carbonate melts as the medium for the formation of diamonds in the Earth's mantle: an experimental study". Lithos. 60 (3–4): 145. Bibcode:2002Litho..60..145P. doi:10.1016/S0024-4937(01)00079-2. 
  2. ^ M. G. Loshak and L. I. Alexandrova (2001). "Rise in the efficiency of the use of cemented carbides as a matrix of diamond-containing studs of rock destruction tool". Int. J. Refractory Metals and Hard Materials. 19: 5. doi:10.1016/S0263-4368(00)00039-1. 
  3. ^ R. Abbaschian; et al. (2005). "High pressure–high temperature growth of diamond crystals using split sphere apparatus". Diam. Rel. Mater. 14 (11–12): 1916. Bibcode:2005DRM....14.1916A. doi:10.1016/j.diamond.2005.09.007. 

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